Posted
by
Soulskillon Friday September 23, 2011 @11:36AM
from the rock-em-sock-em dept.

RogerRoast sends this quote from the MIT News Office:
"As intuitive as it seems to a human being, spontaneously planning a trajectory around obstacles in free space is a monstrously complex computation. As a consequence, most motion-planning algorithms give up on the idea of finding the most efficient path between the robot’s initial state and its goal, settling for any path that won’t introduce collisions. [Researchers at MIT] have built a new robotic motion-planning system that calculates much more efficient trajectories through free space. ... Not only do robots guided by the system move more efficiently, saving time and energy, but they also move more predictably (PDF), a crucial consideration if they're to interact with humans."

Apparently, including the mods. I foresaw that and included a smiley, but it didn't help.In fact, having kids seems to correlate with a low sense of humour (or lack of ability to simply ignore a joke they can't laugh about). Sadly, I've seen this in real life as well. I'm pretty sure the GP was able to laugh about the dumbest jokes until approx. 9 years ago.

can't blame you since the summary is a bit misleading, but this is not really about "path finding" in the sense of navigating a body around an environment, it's about efficient movement of a manipulator at the end of a robot arm to get to it's target. Every joint that introduces a degree of freedom (this robot had 7 DOF arms) makes that calculation more difficult.

Closest analog I can think of is something like a back hoe operator. The difference between a good one and someone just learning is huge in terms

I was at an industrial robotics trade show years ago, and there was one spray-painting an auto bumper that amazed me how gracefully it moved; at the end of a swing left-to-right, it turned its wrist at the same time it reversed the arm direction. The only word I could apply was "graceful". Later, I found out it had been trained by a human operator, so it was just mimicking what a human spray-painter with years of practice would do.

Over twenty years ago I was told a story about a ceramic company selling dinnerware such as plates, bowls and dishes and the marketing on the box said "Hand Painted". That the plates were painted by robotic hands obviously wasn't mentioned.

"As intuitive as it seems to a human being, spontaneously planning a trajectory around obstacles in free space is a monstrously complex computation"

I was going to say a similar thing; observe any major highway in any major city in the USA and you will realize that many many people are absolutely terrible at "planning a trajectory around obstacles in free space"... So bad that it causes as many as 90 deaths *every day*.

Not helping that our sensory processing is not really built for anything beyond a walk. Running, much less driving a vehicle at highway speed, can't be properly processed beyond a straight and flat path.

You think they are being inefficient because you don't understand the constraints; in particular any carpeted are of floor is "red hot lava" and sofas are bouncy, allowing "slingshot" style trajectories that would be the envied by NASA.If your children are not human, what does that make you ?

That's a neat result. I used to work on that problem. Today's solutions use a lot more compute power, but now that's available. Early approaches to this problem worked by treating it as a maze problem in N-dimensional configuration space and running a maze solver. Latoumbe at Stanford was behind a lot of that. That approach became combinatorialy infeasible as N increased. Newer techniques are more like a random greedy search. That works, but the paths aren't all that great. This latest solution seems to improve on random greedy search. That makes sense.

No, it's an N-dimensional configuration space. This is a variation on the Piano Mover's Problem. [wolfram.com]

Visualize getting a point-sized object through a maze. The maze can be treated as a graph, with junctions as graph nodes. All dead end links and closed subgraphs not containing the endpoints can be discarded. What remains contains a usable path. Then you use a path finding graph algorithm. If links have costs, there are ways to find an optimal or (with much less work) a near-optimal solution.

In a research family tree point of view, he's behind this too. The MIT algorithm is a modification of RRT that instead of using one-connectedness uses k-connectness like PRM. RRT is from LaValle and Kuffner, who were Latoumbe's students at Stanford. PRM is from Lydia Kavraki, who was also Latoumbe's student at Stanford.

The PR2 video was kind or irksome, because they chose the very first version of RRT (circa 2000) to compare against their new algorithm, rather than a number of variants that became availa

Darn it, I bought this inexpensive prosthetic arm from a bootlegger/bootarmer somewhere in Asia and sometimes it flails uncontrollably for between 0.5 and 2 seconds. I'm truly sorry it spilled your snack and you missed that scene. May I compensate you for the wasted theater popcorn? FWIW, my wife can't sleep in the same bed with me if I've forgotten to remove it, if that's any consolation.

However, if it's that meaningless, wouldn't it also be as meaningful as hell? I don't want to perpetuate the redundancy of its meaninglessness when it's equally as meaningful. Heh. Oh, ouch. I really need to wake up before I type myself into a lake of logorrhea.

I suggest this is the start to the long road described in the short story "The Feeling of Power" by Isaac Asimov. In the future someone will re-invent the art of human computation, and manned missiles (and thus human computing of trajectories) will follow.